1. (a) Field of the Invention
The present invention relates to the control apparatus of a vacuum cleaner having a fuzzy inferring device for performing fuzzy inference.
2. (b) Description of the Related Arts
Recently, in the control apparatus of a vacuum cleaner, a sensor detects a physical quantity to be controlled and the operation of a load is controlled by fuzzy inference according to the output of the sensor.
Referring to FIGS. 12 and 13, a conventional control apparatus of an air cleaner, having a sensor, for controlling the number of rotations of a motor is described below as an example of the control apparatus of an electrical appliance of this kind.
A gas sensor 21 detects the concentration of gas in air, thus converting the concentration into an electric signal such as a voltage. The gas sensor 21 outputs an electric signal to a fuzzy inferring device 22. The fuzzy inferring device 22 performs a calculation based on the output of the gas sensor 21 and determines the number of rotations and drive period of time of a fan motor 23, thus outputting the result obtained by the calculation to a control means 24. The control means 24 controls the rotation of the fan motor 23 according to the number of rotations determined by the fuzzy inferring device 22.
The fuzzy inferring device 22 performs a calculation based on fuzzy inference so as to determine the number of rotations of the fan motor 23. Supposing that the output of the gas sensor 21 is at a point (G) shown in FIG. 13, of variation concentration membership functions, the weight of "ordinary" membership function is approximately 2/3 and that of "many" membership is approximately 1/3. The fuzzy inferring device 22 determines the number of rotations of the fan motor 23 in combination of membership functions based on a rule (not shown) of inferring the number of rotations and calculates the center of gravity. In response to the information outputted from the inferring device 24, the control means 24 controls the rotation of the fan motor 23.
According to the above-described control apparatus of the conventional electrical equipment, if the number of membership functions is high, a great amount of storage capacity for memorizing them is required.
Similarly to an air cleaner, vacuum cleaners in which the number of rotations of a motor can be varied are increasingly manufactured with the variety of objects to be cleaned. In using fuzzy inference to control the number of rotations of the motor, the fuzzy inferring device is required to have a large storage capacity is required to store a large number of membership functions.